Causes of colour and fluorescence in speleothems

Abstract Speleothems fluoresce, when illuminated with UV light, between 410 and 460 nm. In this study, we attempted to determine the nature of the fluorophores, thought to be either trace elements or organic matter trapped in the calcite. Fluorescence of solid speleothems and organic species extracted from the calcite were measured to quantify their contribution to the observed fluorescence of the speleothems. All speleothems and extracts gave similar spectra with broad emission maxima centred around 410–430 nm, and two excitation maxima at approximately 255 and 330 nm. The organic compounds were partly characterized using fulvic acid (FA)–humic acid (HA) separation and molecular size fractionation. Trace elements, determined by neutron activation analysis, do not appear to be responsible for the observed spectra. Organic matter, particularly FAs, were found to be the dominant fluorophore in the calcite. Of the FA, the dominant fractions were the hydrophilics. Darker speleothems, although having higher concentrations of FA and HA than light speleothems, had lower emission intensities, due to self-absorption. Average particulate organic matter (POM), FA, HA, and total organic matter (TOM) concentrations for the dark speleothems were twice that of their light counterparts.

[1]  H. Schwarcz.  Chapter 7 – GEOCHRONOLOGY AND ISOTOPIC GEOCHEMISTRY OF SPELEOTHEMS , 1986 .

[2]  R. Creelman.  Handbook of environmental isotope geochemistry, vol. 1. The terrestrial environment: A.P. Fritz and J.Ch. Fontes (editors), Elsevier, Amsterdam, 1980, XII + 532 pp., U.S. $ 90.25/Dfl. 185.00 , 1982 .

[3]  W. Broecker,et al.  Radiocarbon Measurements and Annual Rings in Cave Formations , 1960, Nature.

[4]  C. Clapp,et al.  SIZES AND SHAPES OF HUMIC SUBSTANCES , 1999 .

[5]  E. Weiner,et al.  Fluorescence Spectroscopy in Environmental and Hydrological Sciences , 1993 .

[6]  Michael A. Wilson,et al.  Low molecular weight species in humic and fulvic fractions , 1988 .

[7]  N. Senesi.  Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals : Part I. The electron spin resonance approach , 1990 .

[8]  H. Schwarcz,et al.  Seasonal variability in organic substances in surface and cave waters at Marengo Cave, Indiana , 2000 .

[9]  David A. Pickett,et al.  A High-Resolution Record of Holocene Climate Change in Speleothem Calcite from Cold Water Cave, Northeast Iowa , 1992, Science.

[10]  W. Schlesinger.  Carbon Balance in Terrestrial Detritus , 1977 .

[11]  Otto S. Wolfbeis,et al.  Fluorescence spectroscopy : new methods and applications , 1992 .

[12]  R. C. Reynolds.  Polyphenol inhibition of calcite precipitation in Lake Powell 1 , 1978 .

[13]  N. Senesi.  Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals : Part II. The fluorescence spectroscopy approach , 1990 .

[14]  P. MacCarthy,et al.  Quantitative evaluation of XAD-8 and XAD-4 resins used in tandem for removing organic solutes from water , 1992 .

[15]  Yves Quinif,et al.  Annually laminated sequences in the internal structure of some Belgian stalagmites , 1996 .

[16]  E. Suess.  Interaction of organic compounds with calcium carbonate—I. Association phenomena and geochemical implications , 1970 .

[17]  E. Tipping.  Humic substances in soil, sediment and water: Geochemistry, isolation and characterization edited by G. R. Aiken, D. M. McKnight, R. L. Wershaw and P. MacCarthy, Wiley, 1985. No. of pages: 692. Price: £61.35 (hardback) , 1986 .

[18]  A. Masuda,et al.  The coprecipitation of rare-earth elements with calcite and aragonite , 1988 .

[19]  J. Leenheer,et al.  Comprehensive approach to preparative isolation and fractionation of dissolved organic carbon from natural waters and wastewaters. , 1981, Environmental science & technology.

[20]  L. Tranvik,et al.  Aquatic Humic Substances , 1998, Ecological Studies.

[21]  R. Aller,et al.  The geochemistry of iodine in near-shore carbonate sediments , 1985 .

[22]  O. Rubio,et al.  Fluorescence of tin-sensitized manganese in single-crystalline NaCl. , 1988 .

[23]  H. Schwarcz,et al.  Luminescent microbanding in speleothems: High-resolution chronology and paleoclimate , 1994 .

[24]  R. Mitterer.  Amino Acid Composition of Organic Matrix in Calcareous Oolites , 1968, Science.

[25]  R. F. Christman,et al.  Humic substances and their role in the environment. , 1988 .

[26]  K. Hayase,et al.  Sedimentary humic acid and fulvic acid as fluorescent organic materials , 1985 .

[27]  P. Buurman.  Humic Substances in Soils, Peats and Sludges-Health and Environmental Aspects , 1999 .

[28]  A. Grimvall,et al.  Humic Substances in the Aquatic and Terrestrial Environment , 1991 .

[29]  Richard A. Bourbonniere,et al.  Distribution patterns of dissolved organic matter fractions in natural waters from eastern Canada , 1989 .

[30]  M. Hayes,et al.  Humic Substances from Podzols Under Oak Forest and a Cleared Forest Site I. Isolation and Characterization , 1997 .

[31]  G. Sposito.  The Chemistry of Soils , 2008 .

[32]  D. J. Marshall,et al.  Luminescence Microscopy and Spectroscopy: Qualitative and Quantitative Applications , 1991 .

[33]  M. Gascoyne.  Palaeoclimate determination from cave calcite deposits , 1992 .

[34]  M. Borsaru,et al.  Neutron activation analysis , 1972 .

[35]  J. W. Mcklveen.  Fast neutron activation analysis , 1981 .

[36]  O. Manuel,et al.  IODINE AND URANIUM IN SEDIMENTARY ROCKS. , 1972 .

[37]  M. Heaven,et al.  Electronic spectroscopy and energy transfer pathways of matrix isolated iodine , 1989 .

[38]  Andy Baker,et al.  Annual growth banding in a cave stalagmite , 1993, Nature.

[39]  R. Mason,et al.  Cathodoluminescence activation in manganese-bearing and rare earth-bearing synthetic calcites , 1990 .

[40]  D. Pietrzyk,et al.  Amberlite XAD copolymers in reversed phase gravity flow and high pressure liquid chromatography , 1977 .

[41]  P. W. Carter.  Adsorption of amino acid-containing organic matter by calcite and quartz , 1978 .

[42]  G. Sposito,et al.  Flourescence Spectroscopy of Humic Substances , 1988 .

[43]  H. Fujimori,et al.  Simultaneous Determination of Uranium and HNO3 Concentrations in Solution by Laser-Induced Fluorescence Spectroscopy , 1988 .

[44]  T. Miano,et al.  Nature and origin of organic matter in carbonates from speleothems, marine cements and coral skeletons , 1997 .

[45]  Peter Ralston Hesse,et al.  A Textbook of Soil Chemical Analysis , 1972 .

[46]  L. McGown,et al.  Fluorescence Characterization of IHSS Humic Substances: Total Luminescence Spectra with Absorbance Correction , 1996 .

[47]  H. Schwarcz,et al.  High-precision mass-spectrometric uranium-series dating of cave deposits and implications for palaeoclimate studies , 1989, Nature.

[48]  Diane M. McKnight,et al.  Isolation of hydrophilic organic acids from water using nonionic macroporous resins , 1992 .

[49]  M. Yamaga,et al.  Vibronic structure in the photoluminescence spectrum of Cr3+ ions in garnets , 1989 .

[50]  R. F. Christman,et al.  Aquatic and terrestrial humic materials , 1984 .

[51]  P. Smart,et al.  High-resolution records of soil humification and paleoclimate change from variations in speleothem luminescence excitation and emission wavelengths , 1998 .

[52]  R. Malcolm.  Factors to be considered in the isolation and characterization of aquatic humic substances , 1991 .

[53]  C. Calmon,et al.  Book reviewHumic substances in soil, sediment and water: by G.R. Aiken, D.M. McKnight, R.L. Wersham and P. McCarthy (Eds.), John Wiley and Sons, New York, 1985, xiii + 692 pages, $59.95 , 1986 .

[54]  R. Harmon,et al.  Palaeoclimatic and geomorphic implications of 230Th/234U dates on speleothems from Britain , 1978, Nature.

[55]  H. Machel,et al.  Causes and Emission of Luminescence in Calcite and Dolomite , 1991 .

[56]  P. Smart,et al.  An evaluation of some fluorescent dyes for water tracing , 1977 .